Acid disazo dyestuffs



United States Patent" ACID DISAZO DYESTUFFS Hans Krzikalla, Heidelberg, Tim Toepe], Ludwigshafen (Rhine-Oggersheim), and Bernd Eistert, Ludwigshafen (Rhine), Germany, assignors to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen am Rhine, Germany No Drawing. Application October 10, 1951, Serial No. 250,796

Claims priority, application Germany November 2, 1950 6 Claims. (Cl. 260-155) This invention relates to new acid disazo dyestuifs.

We have found that valuable acid disazo dyestufis are obtained by coupling 1 mol of tetrazotised 2.6-diamino- 1-chlorobenbene-4-sulphonic acid first in an acid medium with 1 mol of Z-amino-8-hydroxynaphthalene-6-sulphonic acid and then in a weak acid or neutral medium with 1 mol of any other azo component containing at the most one sulphonic acid group. The second azo component may be, for example, 2-hydroxynaphthalene and its 6-sulphonic acid, l-phenyl-3-methylpyrazolone-(5), 1 (3' sulpho phenyl)-3-methylpyrazolone-(5), 2.4-dihydroxyquino1ine or 1.3-diketocyclohexane.

The dyestuifs obtained are especially suitable for dyeing leather and are characterised by good fastness to alkali, acid and light.

The following examples will further illustrate this invention but the invention is not limited to these examples. The parts are by weight.

Example 1 222 parts of 2.6-diamino-l-chlorobenzene-4-sulphonic acid are suspended in 480 parts of concentrated hydrochloric acid and 1300 parts of ice and tetrazotised in the usual way with a solution of 144 parts of sodium nitrite in 100 parts of ice-water.

The solution of the tetrazo compound is stirred at to C. into a solution of 239 parts of 2-amino-8-hydroxynaphthalene-6-sulphonic acid in 1000 parts of waterand 100 parts of 40% caustic soda solution. The whole is stirred for about 3 hours until the one-sided coupling to form the monoazo compound is completed.

Meanwhile 144 parts of Z-hydroxynaphthalene are well triturated with 120 parts of 40% caustic soda solution and the mixture brought into solution by the addition of 1000 parts of water. The resulting solution is added to the abovementioned solution of the monoazo compound. It is stirred overnight to complete the coupling.

The disazo dyestufi formed is then precipitated by means of 2000 parts of saturated common salt solution and 1000 parts of solid common salt; it is then filtered ofi by suction and dried.

1020 parts of a bluish-red disazo dyestuif are obtained which is specially suitable for dyeing leather.

The dyestuff has the formula l |IHz 01 Ho N=N N= HOsS OH Example 2 11.1 parts of 2.6-diamino-1-chlorobenzene-4-sulphonic acid are tetrazotised as described in Example 1 and the tetrazo compound is coupled with 14 parts of 2-amino-8- hydroxynaphthalene-6-sulphonic acid in an acid medium.

2,729,630 Patented Jan. 3, 19 56 ice Meanwhile 8 parts of ZA-dihydroxyquinoline are dissolved in parts of water and this solution is added to the abovementioned solution of the monoazo dyestuff.

After completion of the coupling, the resulting disazo dyestuff is precipitated by means of 250 parts of saturated common salt solution and 150 parts of solid common salt. The whole is heated to 50 C. for half an hour, allowed to cool, the bluish-red dyestuif filtered olf by suction and dried. The yield is parts.

The dyestut't' has the formula NH: 01 on N=N N=N H038 OH HO \N baH Example 3 11.1 parts of 2.6-diamino-1-chlorobenzene-4-sulphonic Example 4 Into a solution of the monoazo compound from 11.1 parts of tetrazotised 2.6-diamino-l-chlorobenzene-4- sulphonic acid and 14 parts of 2-amino-8-hydroxynaphthalene-6-sulphonic acid prepared as described in Example 1 there is introduced a solution of 5.6 parts of 1.3-diketocyclohexane in 100 parts of water. The resulting disazo dyestutf is precipitated by the addition of 200 parts of potassium chloride. After drying, '22 parts of a bluishred dyestutf are obtained.

The dyestulf has the formula -N=N \N=N-C/ \CH| HO-b Hz HOzS OH S|O3H H H What we claim is: 1. An acid disazo dyestuff of the general formula N= =N-R H028 on wherein R stands for the radical of a coupling component selected from the group consisting of 2-hydroxynaphthalene and its 6-su1fonic acid, 2.4-dihydroxyquinoline, 1.3-

diketeeyelefi and its 3'=sulf6n're acid.

2. The dyestufi of the formula floss 7 OH 3.. The dyestufif of the formula IIIH: Cl OH 4. The dyestutf of the formula Hot,

'e and 1-pliehyl-3-methylpyrazolone-(5) 4. 5. The dyestufi of the formula 6. A process for the production of acid disazo dyes't'ulfs which comprises coupling I mol of tetrazotised l-chloro- 2.6-diamino-benzene-4-sulfonic acid first in an acid medium with 1 mol of 2 -amino-8-hydroxynaphthalene-6-sulfonic acid and then in a neutral to Weak acid medium with one mol of a coupling component selected from the group consisting of Z-hydroxynaphthdlene and its 6-sulfonic acid, 2.4-dihydroxyquinoline, 1.3-di 1 etocyclohexane and 1-phenyl-3-methylpyrazolone-(5) and its 3-sulfo-nic acid.

References Cited in the file of this patent STATES PATENTS 982,5Q8' Laska '--a- Jan. 24, 1911 2,116,206 Krz'ikalla et at. May 3, 1938 FOREIGN PATENTS Great Britain- Of 

1. AN ACID DISAZO DYESTUFF OF THE GENERAL FORMULA 